Disk drive with improved structure for fastening bearing assembly to rotor and housing

ABSTRACT

A magnetic disk drive device for reading-out/writing-in information on/from a disk which comprises a yoke plate for rotatably supporting an actuator by a pair of bearings; a stopper for restricting the rotation range of said actuator; a solenoid bracket integrated in the yoke plate; a lock mechanism for locking said actuator at the innermost peripheral of the disk; a base plate in which a recess for securing the yoke plate; an air filter formed in V-shape to purifying air in said case; and a back-tension regulating piece in contact with a flexible print board.

This application is a division of application Ser. No. 07/490,111, filedMar. 7, 1990.

FIELD OF THE INVENTION

The present invention relates to a disk drive device effectingread/write of information on/from a disk by means of magnetic heads.

BACKGROUND OF THE INVENTION

There are known disk drive devices using hard type magnetic heads. Adisk drive device of this kind consists principally of at least onemagnetic disk, at least one magnetic head for recording/reproducinginformation on/from this magnetic disk, a spindle motor for driving therotation of the magnetic disk, an actuator drive mechanism for moving(seeking) the magnetic head in the radial direction of the magneticdisk, an auto-retract mechanism for causing the magnetic head to seekthe innermost periphery of the magnetic disk at shut-off, a base plateon which each of the previously-identified components are located, and atop cover covering this base plate.

However, according to such magnetic disk drive devices, since theactuator drive mechanism and the autoretract mechanism are secured tothe base plate by means of screws, it is necessary to mount these partsso as not to contact the magnetic disk. Therefore the regulation of thefunction and the performance of these parts was effected after themounting thereof on the base plate. Further, in an auto-retractingmechanism including a solenoid and a lock lever operated by thesolenoid, there is disposed a coil spring for energizing the lock leverand since the coil spring should be mounted in an energized state, themounting operation is laborious and a large space for setting the coilspring is required, which was an obstacle against compacting the device.Furthermore, in a damper mechanism of an actuator, a swing arm is incontact with a rigid stopper or an elastic stopper and the stoppercondition is the same on the outer periphery side, and on the innerperiphery side. In the case where the rigid stopper is used, it ispossible to obtain a high positional precision both on the outer and onthe inner periphery side, and in the case where the elastic stopper isused, it is possible to increase the performance of the dampermechanism. However, in the present state of techniques, the stoppercondition is satisfied neither on the outer periphery side nor on theinner periphery side. Further, in the magnetic head control mechanism,in order to control the movement of the magnetic head, it was necessaryto make the force applied to a plate-shaped coil uniform over themovement region of the plate-shaped coil and to make the speed of themagnetic head uniform over the movement region. In addition, in aconstruction where an air filter was incorporated in a mold case asshown in FIG. 44, since an air filter unit 202 mounted on the mold caseis fixed to the corner on a base plate 201, in the arrangement forattaching the air filter to a conventional disk drive device as shown inFIG. 44, the number of parts was great and the number of mounting stepswas also great. Furthermore, since the mold case had a certainthickness, the effective area of the air filter was reduced, whichdecreased the purifying action. There was also a concern that the fixingpositions of this mold case could loosen and that inner parts could bedamaged. In addition, since a rotor 20 is directly in contact with outerwheels of bearings 14, 15 in construction of the bearing portion of anactuator in a conventional disk drive device as shown in FIG. 45, thedistance between the rotor 20 and the outer wheels of bearings 14, 15was varied due to the thermal expansion of a rotor and that the pressurefluctuated, which impaired stable rotation of the actuator. In addition,since the rotor 20 slides on the outer wheels of the bearings 14, 15when the rotor is mounted on the bearings 14, 15, there is concern thatthe rotor 20 might be damaged. Furthermore, since a conventional devicehas no back tension adjusting piece as shown in FIG. 46, a flexibleprint board 101 receives a force in the direction F and by elastic forceexpands so that since back tension takes place on the actuator, it isnecessary to set that the back tension to the actuator at 0 when themagnetic head is at the central position of the movement thereof.However the requirement should be effected at the mounting because oferrors, etc. of the parts. Although it is desirable that the backtension is 0 at loading, this regulation is difficult.

OBJECT OF THE INVENTION

The object of the present invention is to provide a disk drive devicecapable of solving the problems described above.

SUMMARY OF THE INVENTION

In order to achieve the above object, a disk drive device according tothe present invention is characterized in that it comprises stoppersdisposed so as to support rotably an actuator on a yoke plate by a pairof ball bearings, on which at least a head is mounted; and forrestricting a domain of rotation of the actuator, a solenoid bracketattached to the yoke plate; a base plate in which a recess is formed tosecure the yoke plate to a position corresponding to the yoke plate, anair filter formed in a V-shape and attached to the corner of the baseplate to clean air in the case, a back tension adjusting piece forsuppressing back tension of the flexible print board taken out from theside of said actuator in a folded manner. Therefore, since the actuatorcan be easily set in place without touching the disk when it is built inthe magnetic disk drive device and each of the mechanisms constitutingthe actuator is unified, each of the mechanisms is adjusted and then isassembled as an actuator to set in a base plate so that assembly work issimple and compactness can be attained. Further, the disk area can beused effectively because stopping conditions of the outer peripheralside and inner peripheral side of said stopper are made different bymeans of simple construction. In addition, since a pin of ball bearingsis unified, the work of assembling the rotor to the bearings andexchanging it therefrom is simple and the rotor is not damaged, and thepositioning precision to the base plate is improved.

Besides, since the number of parts is reduced, the filter area can beenlarged and the falling apart of a filter receiving stage can beprevented. Further, the back tension can be made zero by provision of aFPC back tension adjusting piece and loading to the arm due to flexedforce is suppressed to effect sure head positioning.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a disk drive device according to the presentinvention, in the state where the top cover is removed;

FIG. 2 is an exploded perspective view illustrating the wholeconstruction of the disk drive device;

FIG. 3 is a side cross-sectional view of the actuator unit;

FIG. 4 is an exploded perspective view of the actuator part;

FIG. 5 is a longitudinal cross-sectional view of the bearing part of theactuator;

FIGS. 6 and 7 are a plan view and a bottom view, respectively, of therotor of the actuator;

FIGS. 8 and 9 are plan views of an upper head arm and a lower head arm,respectively;

FIGS. 10 and 11 are perspective views of the upper yoke plate and thelower yoke plate, respectively;

FIG. 12 is a plan view illustrating the state where a permanent magnetis secured to the yoke plate;

FIG. 13 is a plan view showing positional relation of a movable coil andthe permanent magnet;

FIG. 14 is a longitudinal cross-sectional view of a fixed shaft part.

FIGS. 15 and 16 are plan views illustrating modifications of the stoppermechanism of the actuator, respectively;

FIGS. 17 to 20 are a plan view, a front view, a bottom view and across-sectional view along a line A--A of a cable holder, respectively;

FIGS. 21 and 22 are a front view and a bottom view of a cable cramp,respectively;

FIG. 23 is an exploded perspective view of a lock lever driving springpart;

FIGS. 24 to 27 are a plan view, a front view, a bottom view and across-sectional view along a line B--B of the lock lever, respectively;

FIG. 28 is a plan view of the lock lever driving spring part;

FIG. 29 is an enlarged plan view in the neighborhood of the actuator;

FIG. 30 is a plan view of the actuator unit;

FIG. 31 is an enlarged plan view illustrating the state before mountingthe actuator unit;

FIGS. 32 and 33 are a side view and a plan view of a solenoid bracket,respectively;

FIGS. 34 and 35 are a front view and a side view of a cable guide,respectively;

FIG. 36 is a plan view of the FPC;

FIG. 37 and 38 are a plan view and a cross-sectional view along a lineC--C of the base plate, respectively;

FIG. 39 is a bottom view of a top cover;

FIG. 40 is an enlarged perspective view of the air filter receiving partof the top cover;

FIG. 41 is a front view of the air filter;

FIG. 42 is a perspective view of the air filter part;

FIG. 43 is a plan view of the main part of the air filter;

FIG. 44 is a perspective view showing an arrangement where the airfilter is secured to the base plate of a conventional disk drive device;

FIG. 45 is a longitudinal cross-sectional view of the bearing part of aconventional actuator;

FIG. 46 is a plan view of the conventional actuator.

DETAILED DESCRIPTION

The disk drive device indicated in these drawings consists principallyof at least a hard type magnetic disk 1, a magnetic head 2recording/reproducing information on/from this magnetic disk 1, aspindle motor 3 for rotating the magnetic disk 1, an actuator drivemechanism 4 for moving (seeking) the magnetic head 2 in the radialdirection of the magnetic disk 1, an auto-retract mechanism 5 for makingthe magnetic head 2 seek the innermost periphery of the magnetic disk 1at shut-down, a base plate 6, on which they are located, and a top cover7 covering this base plate 6 as shown in FIGS. 1 and 2.

As indicated in FIG. 5, this actuator driving mechanism 4 has a pivotbearing portion 8. A swing arm 9 is supported rotatably by this pivotbearing portion 8 and a magnetic head 2 is mounted at the extremity ofthe swing arm 9 as shown in FIG. 1. Since this magnetic head 2 isrotated around the pivot bearing portion 8, the magnetic head 2 is movedon the surface of the magnetic disk 1 so that the recording/reproductionoperation is effected on a predetermined track.

In the actuator drive mechanism 4 described above and thus constructed,referring to FIG. 5 there is disposed an outer wheel side holder 16, inwhich an engaging hole 17 is formed wherein the outer wheels of a pairof ball bearings 14 and 15 are engaged; a flange 19, for mounting theswing arm, formed on the outer peripheral surface of the outer wheelside holder 16; a rotor 20 constituting this swing arm engaged with theouter peripheral surface of the outer wheel side holder 16 so as to bein contact with the flange 19; an upper head arm 21 and a lower head arm22 formed to be superposed on the rotor 20; furthermore referring toFIGS. 1 and 3, the swing arm 9 consists of: the rotor 20, the upper headarm 21 and the lower head arm 22 superposed on the upper and the lowersurface of this rotor 20, respectively, an elastic gimbal plate 23 madeof stainless steel and secured to the upper head arm 21 and the lowerhead arm 22 by means of screws and two gimbals plates 23 secured to therotor 20 by means of screws. Magnetic heads 2 are mounted on theextremities of these gimbals plates 23. In the case of the presentembodiment, the magnetic heads 2 are so disposed that two of them areopposite to each other on both the sides of each of two magnetic disks1.

The rotor 20 is made of aluminum and a through hole 24 is formed inorder that the pivot bearing portion 8 stated above is inserted thereinas shown in FIGS. 6 and 7. Further threaded holes 25 for mounting thegimbals plates 23, 23 and threaded holes 26 for securing the upper headarm 21 and the lower head arm 22 thereto by means of screws are formedtherein. A ring-shaped recess portion 28 for locating the O-ring 27 ofFIG. 4 is formed around the through hole 24 at the proximity of theouter periphery thereof on the front surface of this rotor 20. From theouter periphery of the rotor 20 extend two supporting arms 30 formounting a ring-shaped moving coil 29.

The upper head arm 21 and the lower head arm 22 are made of aluminum andas indicated in FIGS. 8 and 9, threaded holes 31 for mounting theelastic plate 23 are formed in each. Further through holes 32 and 33 forinserting the pivot bearing portion 8 therein are formed in head arms 21and 22, respectively. The diameter of the through hole 33 formed in thelower head arm 22 is set so as to be greater than the outer diameter ofthe flange 19 of FIG. 5 for mounting the swing arm of the pivot bearingportion 8. Consequently, the flange 19 of FIG. 5 for mounting the swingarm can be inserted in the through hole 33 so that the upper surface ofthe flange 19 for mounting the swing arm is in contact with the lowersurface of the rotor 20 as shown in FIG. 5. Furthermore, referring toFIG. 9, cut-out portions 34 are uniformly distributed on the peripheryof the through hole 33 in the lower head arm 22 and corresponding tothese cut-out portions 34 there are formed threaded holes 35 on thelower surface of the rotor 20 in FIG. 7. By screwing a screw 36 in eachof the threaded holes 35 through each of the cut-out portions 34, theflange 19 for mounting the swing arm is secured by a half of the headportion of the screw 36 shown in FIG. 4 and the lower head arm 22 issecured by the other half of the head thereof to the lower surface ofthe rotor 20. On the other hand, the upper head arm 21 is disposed onthe upper surface of the rotor 20 by means of screws. The O-ring 27 isheld in the ring-shaped recess portion 28 formed in the rotor 20 by thishead arm 21 as indicated in FIG. 5.

In this way, the ball bearings 14 and 15 are blocked together with theinner and the outer wheel holder 10 and 16 and thus the mountingprecision of the ball bearings 14 and 15 is improved. Further, since therotor 20 is fixed only on the flange 19 of the outer wheel side holder16 by means of the screws 36, even if thermal expansion of the rotor 20takes place, the rotor 20 is expanded and contracted along the outerperipheral surface of the outer wheel side holder 16 and the thermalexpansion has no influences on the positional precision of the ballbearings 14 and 15 engaged with engaging holes 17 formed in the outerwheel side holder 16. Further, since the distance between the magneticheads 2 mounted on the rotor 20 as well as the upper head arm 21 and thelower head arm 22 varies only slightly, even if the rotor 20 iselongated and contracted by the thermal expansion, and the position ofeach of the magnetic heads in the seeking direction remains unchanged,the thermal expansion has no influences on the recording/reproducingoperation on the magnetic disk 1 by means of the magnetic heads 2. Also,since the upper head arm 21 and the lower head arm 22 are disposed so asnot to cover the upper and lower openings of the engaging hole 24 formedin the rotor 20, the ball bearings 14 and 15 can be separated farther byan amount corresponding to the thickness of the upper head arm 21 andthe lower head arm 22 so as to increase the pitch and in this way it ispossible to eliminate unintentional movement in the rotation of theactuator and to stabilize it. Since a pivot bearing portion 8 having theball bearings 14 and 15 is secured to the rotor 20 by means of screws 36together with the lower head arm 22, the mounting work is simple andreplacement is easy. Still further, in the replacement of the rotor 20,the rotor can be simply mounted and dismounted without applying anyundue force thereto and therefore the rotor 20 is damaged less.Furthermore, since the inner peripheral face of the O-ring is in contactwith the outer wheel side holder 16 of the pivot bearing portion 8, therotor 20 can be mounted without any play by using the O-ring 27 so thata stable movement of the actuator can be obtained. In addition, since anupper pole 37 is mounted by screws 12, which are flush head screws, theforce in the horizontal direction on the upper pole 37 acts on the pivotbearing portion 8 in the axial direction through the tapered surface ofthe head portion o(the flush head screws as that it is possible toprevent unintentional movement of the center of rotation of the pivotbearing portion. Furthermore, since the ball bearings 14 and 15 arefirmly mounted at a predetermined position, it is possible to obtain adisk drive device rapidly supported against shock.

An upper yoke plate 37 and a lower yoke plate 38 as described after aredisposed on the upper and the lower end of this pivot bearing portion 8,as indicated in FIGS. 3 and 5. The securing screw 12 stated above isinserted in a through hole 39 formed in this upper yoke plate 37. Thissecuring screw 12 is inserted further through a through hole 11 formedin the inner wheel side holder 10 and a through hole 41 formed in thelower yoke plate 38 and screwed in a threaded hole 42 formed in the baseplate 6, which is on the lower surface of the lower yoke plate 38 sothat the pivot bearing portion 8 is secured to the base plate 6.

The upper yoke plate 37 and the lower yoke plate 38 are constructed bysoft iron plates approximately pieshaped as indicated in FIGS. 10 and11, with thinner portions 45, in which the through holes 39 and 41,respectively, are formed. The arc-shaped sides of the upper yoke plate37 and the lower yoke plate 38 have thicker portions 46, in which aplurality of recess portions 47 are formed in the lower surface of theupper yoke plate 37 and the upper surface of the lower yoke plate 38which are opposite to each other towards the center plane. The pluralityof recess portions 47 are formed at positions corresponding to thecenter of the region of movement of a moving coil 29 on the upper yokeplate 37 and the lower yoke plate 38 and at the same time a permanentmagnet 48 is fixed by adhesion with epoxy so as to cover these recessportions 47 as shown in FIG. 13 and 14. In this way, since the recessportions 47 formed in the upper yoke plate 37 and the lower yoke plate38 can be utilized as an adhesive pool, the contact between thepermanent magnet 48 and the upper yoke plate 37 as well as the loweryoke plate 38 is improved and the strength of the adhesion is increased.

Since these recess portions 47 are disposed on the upper yoke plate 37and the lower yoke plate 38, if differences in various conditions(design error or modification of variable angle, torque, linearity,etc.) are minimal, and since it is possible to combine the upper andlower yoke plates 37, 38 and the permanent magnet 48 by varying theconditions of formation of recess portions 47 in the upper yoke plate 37and the lower yoke plate 38 while keeping the specification of thepermanent magnet 48 constant, it is possible to standardize the form andthe size of the permanent magnet 48 and to effect easily designmodifications by varying the conditions of formation of the recessportions 47.

In this way, since it is possible to reduce magnetic force in thecylindrical recesses 47 at position corresponding to the permanentmagnet 48, by increasing the size of the recess portions 47 on the upperyoke plate 37 and the lower yoke plate 38. The magnetic flux density canbe made approximately uniform in the region of movement of the movingcoil 29 on the permanent magnet 48 as shown in FIG. 3. In this way, theforce acting on the moving coil 29 can be made approximately uniform inthe region of movement of the moving coil 29.

Although the recess portions 47 are formed in the form of circles in thepresent embodiment, the present invention is not restricted thereto. Forexample, the recess portions 47 may have various forms such asrectangles, etc. Furthermore, there may be disposed one or a pluralityof recess portions 47 and the depth of the recess portions 47 may beuniform or different. In addition, the recess portions may be parallelholes or tapered holes.

Since the fixed shaft 50 for fixing the upper and lower yoke plates 37,38 is so formed that the outer diameter of the two end portions aresmaller than the central portion, as indicated in FIG. 14, the distancebetween the upper yoke plate 37 and the lower yoke plate 38 isdetermined by the upper and lower ends of the large diameter portion 51.The lower end portion of the fixed shaft 50 inserted in the mountinghole 49 formed in the lower yoke plate 38 is fixed by splaying thebottom end outside as indicated in FIG. 14. In the insertion hole 52formed in this fixed shaft 50, a screw 53 having a diameter, which issomewhat smaller than the inner diameter of the insertion hole 52, isinserted and the screw 53 is screwed in a threaded hole formed in thebase plate 6 under the lower yoke plate 38. A cylindrical stopper 55made of rubber, etc. is mounted on the large diameter portion 51 of thisfixed shaft 50 and the outer ends of the supporting arms 30 of the rotor20 are made in contact with this stopper 55 so that the domain ofrotation of the rotor (actuator) is restricted.

FIGS. 15 and 16 show different variations of the stopper. In FIG. 15, apair of restricting pieces 56 are extended from the swing arm 9 and astopping body 57 is disposed between these restricting pieces 56. Thisstopping body 57 includes a small shaft 58 standing on the lower yokeplate 38 or on the base plate 6 and an elastic member 59 having acircular or approximately elliptic cross-section, in which the smallshaft 58 is inserted. The small shaft 58 is inserted in this elasticmember, deviated from the center thereof. Consequently, the thicknessesof the parts of the elastic member 59, which are in contact in the tworestricting pieces 56, 56 are different and thus it is possible to varythe condition at the collision of the arm for the inner periphery sideand for the outer periphery side of the disk. Since the thickness is setsmaller for the outer periphery side than for the inner periphery side,the positional precision and the damper function is obtained on theouter periphery side and the damper function is obtained on the innerperiphery side. Therefore the magnetic disk area can be utilized withhigh efficiency. Further, since the outer peripheral side is madethinner than the inner peripheral side, positional precision and damperfunction in the outer peripheral side and damper function in the innerperipheral side can be obtained so that the magnetic disk area can beefficiently utilized. Further, in this case, the rotor 20 is not incontact with the fixed shaft 50, as described previously.

The difference in the device indicated in FIG. 16 from that indicated inFIG. 15 consists in that the small shaft is disposed at the center ofthe elastic member 59 and that an elastic member 60 is disposed fixedlyon the restricting piece 56 corresponding to the inner periphery side.This disposition has the same effect as that described in the precedingembodiment.

Reference numeral 61 represents a cable holder. This cable holder 61 ismade of polyacetal in FIG. 4. As indicated in FIGS. 17 to 20, this cableholder 61 consists of a contact surface 62, which is made to contactwith the side wall of the rotor 20, a mounting hole 63 formedapproximately at the center of this contacting surface 62, a lockingplate 64 disposed; extending from the upper surface thereof in thedirection opposite to the contacting surface 62, with which a lockingpiece described later is engaged, and a mounting surface 66 for thecable guide 65 of FIGS. 21 and 22, which is formed on the oppositesurface from the contacting surface 62. The cable clamp 65 is made of astainless steel plate and it consists of a pair of bent mounting pieces67 formed at the central portion by bending a pair of side portions,which are opposite to each other, a bent portion 68 formed in the formof a ledge and a bent portion 69 formed by bending a side portion at anangle to the main body of the cable guide opposite to the ledge 68 asshown in FIGS. 21 and 22, and a circular hole 70 formed correspondinglyto the mounting hole 63 formed in the cable holder 61. An FPC describedlater is put between the mounting surface 66 of this cable holder 61 andthe cable clamp 65 and one end portion of this FPC is bent around to thecontacting surface 62 of the cable holder 61, which is put between thecable holder 61 and the rotor 20. Then one end portion of the FPC issecured to the rotor 20 by inserting a screw through the circular hole70 and the mounting hole 63 and screwing into a threaded hole formed ina side surface of the rotor 20.

The autoretract mechanism 5 shown in FIG. 1 consists principally of asolenoid, a locking lever 72 driven by this solenoid 71, and a spring 73as indicated in FIG. 23. This locking lever 72 is made of, for example,polyacetal and as shown in FIGS. 24 to 27, consists of a bearing portion75, through which a stud 74 is inserted, a ring-shaped recess portion 76formed in a coaxial circular shape on the upper surface of this bearingportion 75, a cut-out portion 77 for exposing a spring, which portion isformed by cutting off a part of the ring-shaped recess portion 76, alocking piece 78 engaged with a locking plate 64 mounted on the rotor 20described above, an engaging portion 80 for engaging a driving shaft 79of the solenoid 71 referring to FIG. 28, formed by cutting off the lowerend portion of this locking piece 78, and a mounting portion 82 formounting a balancer 81 made of tungsten and disposed on the side, whichis opposite to the locking piece 78, as indicated in FIGS. 24 to 27. Thelocking lever 72 is so constructed that it is balanced around the centerof rotation owing to this balancer 81. In FIG. 23, a spring 73 isdisposed in the ring-shaped recess portion 76 of this lock lever 72. Thetwo end portions 84 and 85 of this spring 73 are bent downward. One ofthe ends 84 is engaged with the locking piece 78 and the other end isengaged with a protruding surface of a driving shaft, 79 of the solenoid71. Since one end 84 of this spring 73 is engaged with the locking piece78; as indicated in FIG. 28, and the other end 85, which is in the freestate, is engaged with the solenoid 71 (position in the provisionalmounting state); and further the solenoid 71 is positioned in themounting state, the locking lever 72 is energized counterclockwise bythe spring 73 and the driving shaft 79 of the solenoid 71 engaged withthe engaging portion 80 of the locking lever 72, as indicated in FIG.28, and is drawn-out by the non-energized solenoid 71. Further, the stud74 is inserted through the bearing portion 75 of the locking lever 72and the extremity of the stud 74 passing through an elongated hole 83formed in the lower yoke plate 38 is screwed in the mounting threadedhole 88 (not shown) formed in the solenoid bracket 86. The lower end ofthis stud 74 is formed so as to have a smaller diameter, as indicated inFIG. 23, so that the height of the stud 74 at screwing is regulated andthat there exist gaps at the upper and the lower extremity of thelocking lever 72. In this way, the locking lever 72 is rotatable aroundthe stud 74. The ring-shaped recess portion 76 is covered by the headportion 74a of the stud 74 so that the spring 73 of the ring-shapedrecess portion 76 is secured therein.

The solenoid bracket 86 is made of an aluminum plate. It has a bottomplate 89 as indicated in FIGS. 32 and 33, and in this bottom plate 89,there are formed the through hole 88 described above, solenoid mountingholes 90, a hole 91 for mounting on the base plate 6, a hole 93 forsecuring a screw 92 passing through the lower yoke plate 38, a spillport 94 for the FPC connector terminal of the solenoid, etc. Further, astopping piece 95 for restricting the region of movement of the lockingpiece 78 of the locking lever 72 is formed on the bottom plate 89 bybending a part thereof. A mounting piece 97 for mounting a cable guide96 is formed on the bottom plate 89 by bending a part thereof.Protrusions 98 are disposed at the upper end of this mounting piece 97as indicated in FIG. 33. A threaded portion 99 is formed at the nearlycentral portion of the mounting piece 97. The cable guide 96 is formedin a rectangular plate as indicated in FIGS. 34 and 35, and on the upperedge thereof there is formed a bent piece 100 by bending a part of theplate. Further a piece 102 regulating the back tension of a flexibleprint board (FPC) is formed at one edge by bending it. This back tensionregulating piece 102 regulates the back tension of the FPC 101 of FIG.36 caused by the actuator. The leading angle of the FPC 101 can bevaried by varying the bending angle of the back tension regulating piece102 with respect to the FPC 101, which is in contact with the inner sideof the back tension regulating piece 102 as indicated in FIG. 30. Inthis way, since the bending of the FPC 101 can be varied, the backtension of the FPC 101 can be adjusted. Consequently, the back tensionis eliminated so as to be 0 by bending the back tension regulating piece102 opposite to the direction, in which the back tension is applied bythe actuator. A small hole 103 is formed in the back tension regulatingpiece 102, corresponding to the threaded portion 99 formed in themounting piece 97 stated above. The FPC 101 is put between the mountingpiece 97 and the back tension regulating piece 102 and secured there bymeans of screws. Further, since a part of the flexible print board 101is covered by the back tension regulating piece 102, the latter has ashielding action against external noise and thus self cross-talk can beprevented. Holes 104, through which screws are inserted, and a mountinghole 105, are formed in this FPC 101 as indicated in FIG. 36.

The base plate 6 is formed in an approximately rectangular plate shapeby aluminum die casting. As indicated in FIGS. 37 and 38, there isdisposed a pie-shaped stepwise recess portion 106 on the upper surfaceof the base plate 6 as shown in FIGS. 37 and 38. The lower yoke plate 38constituting the actuator drive mechanism 4 is located in this stepwiserecess portion 106. At the same time, the screw 42 stated above isscrewed in the stepwise recess portion 106 and the mounting screw 12 anda screw 53 are screwed in threaded holes 54. Further, a circular hole108, wherein the spindle motor 3 is mounted, is formed in the base plate6 and threaded holes 109 for motor mounting screws, are formed in theperiphery of this circular hole 108. In addition, there is disposed anapproximately triangular recess portion 110 for mounting the air filterdescribed later at a corner on the upper surface of the base plate 6. Aledge portion 111 is formed at the edge portion on the upper surface ofthe base plate 6 and a gasket 112 not shown is disposed in this ledgeportion 111. Reference numeral 113 is a threaded hole disposed on thebase plate 6. A screw 114 is screwed in this threaded portion 113through a hole 9 for mounting the solenoid bracket 86 and a hole 105 formounting the FPC 101. Reference numeral 115 indicates threaded holesformed in the ledge portion 111 of the base plate 6 and fixing screws116 for fixing the top cover 7 are screwed in these threaded holes 115.

The clamping portion of the magnetic disk 1 is disposed on the upperextremity of the driving shaft of the spindle motor 3 as shown in FIG.2. This clamping portion is so constructed that the driving shaft isinserted in two magnetic disks 1 putting a spacer therebetween andfurther a fixed plate 118 is disposed over the upper magnetic disk 1 andthat a fixing screw 119 not shown is inserted through this fixing plate118 and screwed in the threaded portion 120 formed in the upper endsurface of the driving shaft. Still further cut-off portions 121 areformed in the base plate 6 so that no fingers contact the magnetic disk1 at the clamping.

The top cover 7 is formed in a rectangular parallelpiped, whose lowerside is opened, by aluminum die casting and as indicated in FIGS. 39 and40, the lower end surface of the top cover 7 is located on the ledgeportion 111 of the base plate 6 through the gasket 112 described above.Consequently, the parts described above disposed on the base plate 6 areenclosed in a space formed by the base plate 6 and the top cover 7 sothat no dust can penetrates therein. Further, the air filter 122 of FIG.41 is located in this space.

This air filter 122 is formed in a rectangular plate by laminatingfiltering material made of polypropylene with a polyester film asindicated in FIG. 41. This air filter 122 is flexible and twice-foldedalong the center line so as to be V-shaped. Then it is located in areceiving portion of the top cover 7. As indicated in FIGS. 42 and 43,this receiving portion is disposed on the inner surface of the top cover7, corresponding to the recess portion 110 of the base plate 6. Furtheran air stream path is formed in this top cover 7 by disposing a negativepressure generating fin 123 along the outer periphery of the magneticdisk 1. Grooves 127 and 128 are disposed on the rear side of one end ofthe negative pressure generating fin 123 forming this air stream pathand a protrusion 129 of the side plate 124. At the same time, a V-shapedholding portion 126 is disposed at the bottom of the air stream path anda recess portion 110 is formed at the position of the base plate 6corresponding to this holding portion 126. The two ends of the airfilter 121 folded in a V-shape are inserted in the grooves 127 and 128and at the same time the two side extremities are inserted in theholding portion 126 and the recess portion 110. Since the air filter 121is received in this state, the air filter 121 can be directly mounted onthe top cover 7 and the base plate 6 without any mold case, which hasbeen required according to the prior art techniques. Consequently, thenumber of parts can be reduced and the mounting operation can besimplified. In addition, the air filter 121 will not loosen or detachduring use and thus will not damage the magnetic disk 1. Further, sinceno mold case is required, the area of the air filter 121 can be utilizedefficiently, which improves the filter efficiency.

Now, the operation of the autoretract mechanism 5 will be explained.

When the disk drive device is switched-on, current flows from thecontrol section not indicated in the figures to the solenoid 71 topull-in the driving shaft 79 referring to FIG. 28. Consequently, thelocking piece 78 of the locking layer 72 coupled with the driving shaft79 is pulled-in by this driving shaft 79 against the elastic force ofthe spring 83 and the locking lever 72 is rotated clockwise in FIG. 29around the stud 74. By this rotating operation, the locking piece 78 ispositioned outside of the region of movement of the locking plate 64 bythe seek of the actuator and the actuator is rotated by the voice coilmotor so that the magnetic head 2 can be moved over the magnetic disk 1.

On the other hand, when the disk drive device is switched-off, counterelectromotive force is generated in the spindle motor and the swing arm9 makes the magnetic head 2 seek towards the inner periphery of themagnetic disk 1 by this counter electromotive force. At the same time,since the current flow through the solenoid is stopped, the lock lever72 is rotated counterclockwise around the pin 74 by the energy stored inthe spring 73 and the locking piece 78 as well as the extremity of thedriving shaft 79 are made to contact the stopper piece 95 of thesolenoid bracket 86 to be stopped there. At this position, since theextremity of the locking piece 78 is engaged with the locking plate 64of the actuator, the actuator is locked at the innermost peripheryportion of the magnetic disk 1. According to the autoretract mechanismdescribed above, since the spring 73 is biased at the state, where thespring 73 is mounted on the ring-shaped recess portion 76, (provisionalmounting state), bending degree of the protruding end up to the positionin the mounting state is small. Therefore the mounting is terminated,when the solenoid 71 is slid and fixed by screwing, and thus themounting is easy. Further, since the spring 73 is located in theringshaped recess portion 76, the spring 73 is incorporated in thebearing portion 7. Consequently, the spring 73 can be located in a smallspace and it is possible to form the device in a compact form. Further,since the opening of the ring-shaped recess portion 76 is covered by thehead portion of the stud 74, it is not anticipated that the spring 73located in the ring-shaped recess portion 76 will break out therefrom.Also, since the stud 74 is constructed so as to be fixed by screwing,the mounting and dismounting of the stud 74 is simple and themaintenance is easy.

In addition, since a weight balancer 81 having the same rotationalinertia as the mass of the driving shaft 79 of the solenoid 71 isinserted in the lock lever 72 under pressure to be mounted there, therotating operation of the locking lever 72 is stable. Since the lockinglever 72 and the locking plate 65 are made of polyacetal resin, nolubricant such as grease is necessary for the locking piece 78, whichproduces slight shavings.

Since the solenoid bracket 86 is so constructed that the position can bechanged more or less with respect to the lower yoke plate 38, the playat the autoretract of the actuator, i.e. undue rotational freedom whenthe locking piece 78 is engaged with the locking plate 65, can bereduced as much as possible.

Next the mounting direction of the actuator drive mechanism 4 and theautoretract mechanism 5 will be explained.

As indicated in FIG. 30, the voice coil motor portion consisting of themoving coil 29, the permanent magnets 48, the swing arm 9, theautoretract mechanism 5, the fixed part of the FPC 101 and the headamplifier are constructed in one body, i.e. assembled as one unit.Consequently, the parts, for which the function and the performance ofvarious elements, which are assembled in one unit, can be mounted in thebase plate 6. At the mounting of this unit, at first at the lower endportion 44 of the protrusion 8 protruding from the lower surface of thelower yoke plate 38 is engaged with the circular recess portion 43formed in the base plate 6 so as to position the center of rotation ofthe actuator (refer to FIG. 31 and FIG. 5). In this state, the insertionhole 52 of the fixed shaft 50 of FIG. 14 is separated from the threadedhole 54 formed in the base plate 6. When the actuator is rotatedcounterclockwise from this state, the magnetic head 2 on the actuator isdisplaced towards the inner periphery of the magnetic disk 1. Then theouter extremity of the supporting arm 30 on the rotor 20 of the actuatoris in contact with one of the fixed shafts 50 and the upper yoke plate37 as well as the lower yoke plate 38 are rotated counterclockwisearound the lower end portion 44 stated above. Then, at the mechanicalstop position (the disk and the magnetic head are in contact with eachother in a non-read/write area of the innermost peripheral side of thedisk) of the magnetic head 2, the insertion hole 52 for the fixed shaft50 and the threaded hole 54 formed in the base plate 6 are madeapproximately in alignment with each other and the fixed shafts 50 aresecured to the base plate 6 by means of screws 53. At this mounting, theswing arm 9 is over-rotated with respect to the center line of thedomain of rotation thereof. For this reason, a stopper (side wall of therecess portion 106) is disposed on the base plate 6 so that the swingarm 9 is not over-rotated and that the magnetic disk 1 is not disturbedat the mounting of the unit. Further, since there is disposed aclearance for the fixed shaft 50 in the radial direction of the screw53, the regulation of the relative position of the magnetic head 2 tothe magnetic disk 1, i.e. regulation for positioning the magnetic head 2at the tolerable outermost periphery of the magnetic disk 1, ispossible.

The solenoid bracket 86 is secured by the mounting threaded hole 88 bymeans of the stud 74 by screwing. This stud 74 passes through thebearing portion 75 of the locking lever 72 and the elongated hole 83 ofthe lower yoke plate 38, and is screwed in the mounting threaded hole88. Further, the spring 73 is located in the ring-shaped groove 76formed in the bearing portion 75 and the two ends of the spring 3 areengaged with the two edges of the cut-out portion 77. This engagement iseffected by varying the position of the protruding end of the spring 73in the free state, as indicated in FIG. 28, against the elastic force ofthe spring 73. This state is the provisional mounting state of thespring 3. The protruding end of the spring 73 is engaged with theprotruding surface of the driving shaft 79 of the solenoid 71 mounted onthe solenoid bracket 86 so as to energize the spring 73. The drivingshaft 79 is mounted so that the extremity thereof is engaged with thelocking piece 78 of the locking lever 72. Consequently, the energystored in the spring 73 acts on the locking lever 72 so as to rotate itcounterclockwise around the stud 74 so that the extremities of thelocking piece 78 and the driving shaft 79 are made in contact with thestopping piece 95 of the solenoid bracket 86. Since the solenoid bracket86 is rotatable around the stud 74 with respect to the lower yoke plate38, the angular regulation can be varied with respect to the lower yokeplate 38 mounted on the base plate 6 as indicated above. That is, whenthe solenoid bracket 86 is rotated around the stud 74, the locking piece78 of the locking lever 72 is also rotated around the stud 74. By thisrotation, since the locking piece 78 can be located within the region ofmovement of the locking plate 64 of the actuator, the solenoid bracket86 is secured to the base plate 6 and the lower yoke plate 38 by meansof the stud 74 and the screw 92 by screwing, after having been rotatedto where the locking piece 78 is within the region of movement of thelocking plate 64 such that it will be out of the region of movement whenthe solenoid 71 is energized to pull-in the driving shaft 79.

Furthermore, since each of the mechanisms is made in the form of a unit,the function, the performance, i.e. the latching function, thelinearity, the torque, etc. can be regulated for every mechanism, andthey can be mounted on the base plate 6 as a functioning unit alreadycalibrated, which simplifies the adjustment after the mounting.

As explained above, according to the present invention, it is possibleto easily mount the actuator without disturbing the disk at mounting,and at the same time, since each of the mechanisms constituting theactuator is made in the form of a unit, the mounting operation is easyand it is possible to make the disk drive in a compact form by mountingthe actuator unit on the base plate after having calibrated everymechanism. Further, since the stopper conditions can be varied on theouter periphery side and on the inner periphery side of the stopper bodyby a simple construction, the area of the disk can be utilizedefficiently. In addition, it is possible to improve the close adhesionbetween the yoke plate and the permanent magnet by increasing thestrength of the adhesion, which makes it possible to standardize theform and the size of the permanent magnet. Also, since the magnetic fluxdensity can be made approximately uniform within the region of movementof the moving coil, the displacement operation is stabilized. Since thepivot bearing can be unified, the mounting of the rotor of the actuatoron the pivot bearing and the replacement work are simple. Therefore, therotor is not impaired and the positional precision with respect to thehousing is improved.

What is claimed is:
 1. A disk drive device comprising:a pivot bearingportion comprising:antifriction bearings, each with an outer wheel andan inner wheel; and an outer holder with an outer peripheral surfaceincluding a flange portion, said outer holder including an engagingportion with which the outer wheel of the bearings is engaged; and aswing arm supported by the pivot bearing portion, said swing armcomprising:a rotor; and a head arm positioned on and aligned with therotor, the head arm being formed with a hole having cut off portionsformed on its outer edge, wherein the size of the hole is such as toallow the flange portion to pass through and be in contact with therotor; and wherein the rotor is mounted on the flange portion by screwspassing through the cut off portions and being secured in the rotor, andby the screw heads holding the flange portion and the head arm againstthe rotor.
 2. A disk drive device according to claim 1 furthercomprising:a housing with a recess portion, said recess portion having athreaded hole; wherein said pivot bearing portion further comprises aninner holder with a lower end portion, the bearings being engaged withthe inner holder; wherein the lower end portion is engaged with therecess portion and the pivot bearing portion is mounted to the housingby a screw secured in the threaded hole of the recess portion.